With separate type air conditioners, an outdoor unit placed outdoors and an indoor unit installed indoors are connected via a transmission line. Various types of control signals such as operation ON/OFF signals, temperature settings, operation modes, and the like are transmitted by means of this transmission line.
In the past, transmission lines would become tangled in situations in which a large number of indoor units and outdoor units were connected together. In addition, the transmission lines would become tangled in situations in which there is a large distance between the indoor units and the outdoor unit, even if one indoor unit is connected to one outdoor unit.
It is thought that these types of problems will be solved by installing a transceiver unit that transmits and receives control signals in both the outdoor unit and the indoor unit, and transmitting the control signals wirelessly instead of using a wired transmission line.
However, in order to wirelessly transmit and receive control signals between the outdoor unit and the indoor unit, the transceiver units must either have good reception sensitivity or a high transmission output power. When transceiver units having these types of transmission and reception capabilities are used, one problem created thereby is an increase in costs.